1. Field of the Invention
This invention relates generally to the field of well logging and more particularly to a means and method for determining the texture or roughness of the surface of a borehole.
2. Prior Art
Ultrasonic logging tools such as a borehole televiewer provide detailed sensing of the reflectance and topographic properties of a borehole surface. However, in many applications, such as grain size determination or corrosion detection, information regarding the textural properties of the borehole surface on a scale finer than the resolution attainable with such a televiewer is desirable.
When an ultrasonic beam from such a televiewer impinges upon the surface of a borehole, some energy is specularly reflected according to the laws of gometric optics (i.e., in mirror-like manner) and some energy is scattered in all directions. The amount of such scattered energy as compared to that of the specular reflection is controlled by surface roughness or features on a scale comparable to or smaller than the wavelength of the incident ultrasonic energy.
It is therefore a general object of this invention to provide a means and method for making ultrasonic measurements of the energy scattering properties of the surface of a borehole in order to characterize its texture or roughness.
It is a more particular object of this invention to provide an improved means and method for determining the texture of a borehole surface with a high degree of resolution.
Other and further objects and advantages of this invention will become apparent from a consideration of the detailed description to follow taken in conjunction with the appended drawings.